The present invention relates to a charge level sensor for use in electrophotography, electrostatic recording or the like.
Conventionally, in measuring the level of electric charge, there has been employed a method of using a vibrating-reed electrometer or a method of directly measuring a level of electric charge with a Faraday gauge. These methods, however, are disadvantageous as a practical matter because such an electrometer or gauge is large and costly for the above-mentioned applications. Furthermore, the results of such measurements are dependent on the distance between a sample and the sensor and are greatly influenced by strain on the sensor or foreign matter on or in the sensor. For these reasons, the above-described sensors are not practical for use as charge level sensors for an electrostatic image.